The Potential Of Christmas Bird Counts For Monitoring Presence Of Exotic Bird Species

The 1975 Christmas Bird Count was divided into 10 blocks, each comprising 100 observation units, encompassing the continental United States and Alaska. A random sample of 10 observation units was drawn from each block, assuring an even distribution over the continental United States and Alaska. Nine major metropolitan areas which were not drawn in the random sample were also studied. Each unit in the sample was examined for each of the years 1956, 1966, 1973, 1974 and 1975. The occurrence and number of each was recorded for all sample units for all years. Results indicated that a total of 30 exotic bird species were observed in Christmas Bird Counts. The greatest variety of species was found around the major cities studied especially Miami, FL. and Los Angeles, CA. The most abundant and widespread exotic species were the European starling (Sturn us vulgaris), house sparrow (Passer domesticus), pheasant (Ph asianus colchicus), cattle egret (Bubulcus ibis), and house finch (Carpodaeus mexicanus). The present survey did not indicate that all known exotic bird species were detected in Christmas Bird Counts. Nevertheless, Christmas Bird Counts could be a valuable means of monitoring the presence and possible abundance of exotic bird species provided that it is recognized that failure to detect species is not necessarily indicative of the absence of those species.

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